Traders on the floor of the New York Stock Exchange. / Richard Drew, AP

by Adam Shell and Will Cummings, USA TODAY

by Adam Shell and Will Cummings, USA TODAY

Stocks stumbled -- the Nasdaq taking a particular pounding -- after a report indicated that the nation's jobless rate was unchanged for March.

The job market grew, with employers adding 192,000 jobs in March as milder weather helped propel the labor market out of its winter doldrums. But the unemployment rate stayed still because because there were more people looking for jobs, including previously discouraged workers, the Labor Department said Friday.

The Nasdaq composite index was hammered, closing down 2.6%, or about 110 points. The Dow Jones industrial average finished down 1% -- a 160-point loss -- and the S&P 500 ended 1.25% lower -- down nearly 24 points.

Most of the pain was in so-called momentum stocks, which are falling back to earth. Sharp declines in Facebook, Tesla and Amazon, for example, are a signal that froth is coming off one-time highflyers.

The unanswered question is whether the selloff is healthy and simply investors shifting cash into better-valued stocks and sectors - or whether the steep drop is the first sign of trouble for the broader U.S. stock market?